On December 8, 2010, the European Commission (EC) Scientific Committee on Emerging and Newly Identified Health Risks (SCENIHR) approved its opinion on the scientific basis for the definition of the term “nanomaterial.” The opinion concludes that:
- Whereas physical and chemical properties of materials may change with size, there is no scientific justification for a single upper and lower size limit associated with these changes that can be applied to define adequately all nanomaterials;
- There is scientific evidence that no single methodology (or group of tests) can be applied to all nanomaterials; and
- Size is universally applicable to define all nanomaterials and is the most suitable measurand. Moreover, an understanding of the size distribution of a nanomaterial is essential and the number size distribution is the most relevant consideration.
To define an enforceable definition of “nanomaterial” for regulatory use, the opinion proposes to set an upper limit for nanomaterial size and to add to the proposed limit additional guidance specific for the intended regulation. According to the opinion, it is critical that the guidance includes an extended description of relevant criteria to characterize the nanoscale. Merely defining single upper and lower cut-off limits is not sufficient in view of the size distributions occurring in manufactured nanomaterials. Alternatively, a tiered approach may be required depending on the amount of information known for any specifically manufactured nanomaterial and its proposed use.